The present invention relates to a magnet unit containing a magnetic spring device, and more particularly to a magnet unit suitable for being used as a component in a vibration damping apparatus, for instance, such as a suspension unit of a vehicle seat, a train seat, or a boat seat, an engine mount, and the like.
A variety of vibration damping materials, vibration dampers, and control techniques have been commonly used to reduce vibration and noise caused by a machine or an apparatus which itself is typically constructed of a low damping material in order to ensure its rigidity.
Damage to human body and its nervous system due to their exposures to vibration has become a serious problem with the ever increasing vehicle speed. Such a damage shows many symptoms such as fatigue, headache, stiffness of shoulders, lumbago, and amblyopia. In general, vibration isolation is achieved by a damping apparatus with a properly matched spring such as metal springs or air springs and damping materials such as rubber, viscoelastic materials, or dampers. However, the dynamic magnification and the loss factor of the damping apparatus tends to be related to each other. More particularly, a reduction in dynamic magnification to improve low-frequency characteristics of the damping apparatus tends to reduce the loss factor, resulting in the damping apparatus being too firm. An increase in the loss factor of the damping apparatus to improve high-frequency characteristics leads to an increase in its dynamic magnification, resulting in the damping apparatus being too soft and a poor damping efficiency at low-frequency. Many attempts have been made in the prior art to suppress vibration by semi-active control or active control or by using a passive damper containing a dynamic vibration damper.
A vibration damping apparatus containing a magnetic spring device, and having a spring constant (elastic constant) being substantially pseudo-zero by incorporating a damping member such as a metal spring, a rubber material, has been recently disclosed. The present inventors have proposed a variety of the magnetic spring devices and vibration damping apparatus using the magnetic spring devices.
A magnetic spring device creates damping characteristics by utilizing a change of the magnetic field accompanied by relative displacement of a stationary magnet and a movable magnet, caused by an input vibration. In the magnetic spring devices in the prior art, the stationary magnet or the movable magnet is fixed with an adhesive to the stationary holder holding the stationary magnet or the movable holder holding the movable magnet.
Accordingly, whatever the case may be, in the production of the magnetic spring device, it becomes inevitably necessary to provide a bonding process to bond the magnets to the holders respectively. The fixing of the magnet with an adhesive requires to leave the assembly of the magnet and the holder at least for about one day until the adhesive is hardened, thereby causing a disadvantage in regard to the production efficiency. Besides, the spring characteristics (spring constant) and the damping force of the magnetic spring device have been determined by the magnetic force, magnitude, thickness, and the number of poles of the permanent magnet used, and no proposal has been made for adjusting the spring characteristics with other means except the above means. Especially in the present invention, since the stationary magnet or the movable magnet is not fixed with an adhesive, it is not easy to take out these magnets and replace them with other magnets for adjusting its spring constant and damping force.
The present invention has been made to overcome the foregoing disadvantage of the prior art, and its object is to provide a magnet unit which can be used as a magnetic spring device which eliminates the bonding process and simplifies the production process so that the production efficiency is improved.
In addition to improving the production efficiency, it is another object of the present invention to provide a magnet unit of which the spring constant and the damping force can be adjusted by adjusting component members other than the magnet without replacement of the magnet itself.
Still another object of the present invention is to provide a method of producing a magnet unit which eliminates the bonding process and simplifies its production process to improve the production efficiency.
To attain the aforesaid objects, in accordance with one aspect of the present invention, a magnet unit is provided. The magnet unit composes a magnetic spring device which is comprised of a movable member disposed in a relatively movable state to a stationary member, a stationary magnet supported by a stationary holder, and a movable magnet supported by a movable holder, wherein the stationary holder and the movable holder are made of a non-magnetic material, and at least either of the stationary magnets or the movable magnets is made of a magnetic material integrally incorporated when the stationary holder or the movable holder made of a non-magnetic material is molded.
In a preferred embodiment of the present invention, a non-magnetic material making the stationary holder or the movable holder comprises a plastic material.
In a preferred embodiment of the present invention, a thickness adjuster made of a magnetic material is laminated on the stationary magnet to make its thickness substantially equal to the thickness of the stationary holder.
In a preferred embodiment of the present invention, an outer frame made of a magnetic material, laminated on the stationary magnet, and at least a portion of which functions as a yoke is provided.
In a preferred embodiment of the present invention, the outer frame varies the leakage flux amount by changing at least one of the factors among thickness, magnitude, or the number of the outer frames to be disposed so that the magnetic force of the stationary magnet to the movable magnet can be adjusted.
In a preferred embodiment of the present invention, an outer frame made of a magnetic material, laminated on the thick adjuster, and at least a portion of the outer frame functions as a yoke is provided.
In another preferred embodiment of the present invention, the outer frame varies the leakage flux amount by changing at least one of the factors among thickness, magnitude, or the number of the outer frames to be disposed so that the magnetic force of the stationary magnet to the movable magnet can be adjusted.
In a preferred embodiment of the present invention, a slide member which comes in slide contact with the other party of the movable member or the stationary member when the movable member moves relatively is provided at least on either of the movable member or the stationary member.
In a preferred embodiment of the present invention, the slide member is made of a magnetic material.
In a preferred embodiment of the present invention, the slide member is made of a non-magnetic material.
In a preferred embodiment of the present invention, a magnet unit composing a magnetic spring device having two degrees of freedom comprises a pair of the stationary members opposedly disposed at a distance from each other, and the movable member disposed between this pair of the stationary members, wherein the movable member moves relatively in two directions along the opposing face direction of the pair of the stationary members and along the direction intersecting substantially at right angles thereto.
In a preferred embodiment of the present invention, a magnet unit composing a magnetic spring device having two degrees of freedom comprises three or more of the stationary members opposedly disposed at a distance from each other, and the movable member disposed between the adjacent stationary members, wherein the movable member moves relatively in two directions along the opposing face direction of the pair of the stationary members and along the direction intersecting substantially at right angles thereto.
In a preferred embodiment of the present invention, a magnet unit composes a magnetic spring device which is comprised of a movable member disposed in a relatively movable state to a stationary member, a stationary magnet supported by a stationary holder, and a movable magnet supported by a movable holder, wherein the stationary holder and the movable holder are made of a non-magnetic material, at least either of the stationary magnet or the movable magnet is made of a magnetic material integrally incorporated when the stationary holder or the movable holder made of a non-magnetic material is molded, and by changing at least one of the factors among thickness, magnitude, or the number of the outer frames to be disposed, made of a magnetic material, laminated on the stationary magnet, and at least one portion thereof functioning as a yoke, the leakage flux amount is varied so that the magnetic force of the stationary magnet to the movable magnet can be adjusted, thereby the spring characteristics of the magnetic spring device can be adjusted at will.
In a preferred embodiment of the present invention, a magnet unit composes a magnetic spring device which is comprised of a movable member disposed in a relatively movable state to a stationary member, a stationary magnet supported by a stationary holder, and a movable magnet supported by a movable holder, wherein the stationary holder and the movable holder are made of a non-magnetic material, at least either of the stationary magnet or the movable magnet is made of a magnetic material integrally incorporated when the stationary holder or the movable holder made of a non-magnetic material is molded, a slide member which comes in slide contact with the other party of the movable member or the stationary member when it moves relatively is provided at least on either of the movable member or the stationary member, and by selecting and disposing the slide member from that made of a magnetic material or that made of a non-magnetic material, a damping force can be adjusted.
In a preferred embodiment of the present invention, a magnet unit composes a magnetic spring device which is comprised of a movable member disposed in a relatively movable state to a stationary member, a stationary magnet supported by a stationary holder, and a movable magnet supported by a movable holder, wherein the stationary holder and the movable holder are made of a non-magnetic material, at least either of the stationary magnet or the movable magnet is made of a magnetic material integrally incorporated when the stationary holder or the movable holder made of a non-magnetic material is molded, and a plurality of the stationary members are opposedly disposed at a distance from each other, the movable member is disposed between the adjacent stationary members and is relatively movable in the direction along the opposing face direction of the adjacent stationary members, and the spring characteristic of the magnet unit can be adjusted at will by adjusting the number of the stationary members and the movable members to be disposed.
In accordance with another aspect of the present invention, a method of producing a magnet unit is provided. The magnet unit is composed of a magnetic spring device which comprises a movable member disposed in a relatively movable state to a stationary member, a stationary magnet supported by a stationary holder, and a movable magnet supported by a movable holder, wherein a method of producing the magnet unit comprises the steps of; molding the stationary holder or the movable holder using a non-magnetic material while incorporating a magnetic material by means of insert molding; and magnetizing thereafter the magnetic material integrally incorporated therein to form the stationary magnet or the movable magnet.
In accordance with another aspect of the present invention, a method of producing a magnet unit is provided, wherein the non-magnetic material forming the stationary holder and the movable holder comprises a plastic material.
In accordance with another aspect of the present invention, a method of producing a magnet unit is provided. The magnet unit is composed of a magnetic spring device which comprises a movable member disposed in a relatively movable state to a stationary member, a stationary magnet supported by a stationary holder, and a movable magnet supported by a movable holder, wherein a method of producing the magnet unit comprises the steps of; pressing in a magnetic material into a mold during the molding process of the stationary holder or the movable holder using a non-magnetic material before finishing its hardening process to allow the magnetic material to be securely held taking advantage of heat shrinkage at the time of the hardening; and magnetizing thereafter the magnetic material integrally incorporated into the mold to form the stationary magnet or the movable magnet.
In accordance with the above aspect of the present invention, the non-magnetic material to form the stationary holder or the movable holder comprises a plastic material.